1. Field of the Invention
The present invention relates to methods for designing lobe-type rotor. By setting suitable parameters, the method can profile a defined rotor and a conjugate rotor with three or more than three lobes which intermesh and conjugate to each other, and effectively evaluate optimum performance in intermeshing and conjugating; whereby to provide higher compression ratio and larger discharge capacity, secure a smooth process while working chamber undergoing compression and expansion, and reduce leakage, thus can reduce noise and vibration while operation of the rotors.
2. Related Art
A large variety of related lobe-type rotor mechanism are already known that generally include a defined rotor and a conjugate rotor with a single-lobe type, double-lobe type or three-lobe type, and the defined rotor and the conjugate rotor intermesh and conjugate to each other. U.S. Pat. Nos. 1,426,820, 4,138,848, 4,224,016, 4,324,538, 4,406,601, 4,430,050 and 5,149,256 disclose relevant rotors. The rotors of the prior arts have drawbacks that curves of each lobe of the rotors are not continuously and smoothly contacted at the joint between each segment; such drawbacks cause tips of the rotors do not mesh completely with other rotor when they are rotating. Consequently, in applying to machines working as periodical expansion and compression operation, abnormal situations such as noise and vibration may be arisen in working chamber enclosed by the defined rotor, conjugate rotor and inner walls of cylinder. Moreover, inappropriate intermeshing between the rotors increases wear and therefore reduces the durability of operation.
In view of aforesaid disadvantages, U.S. patent application Ser. No. 11/214,876 has disclosed a defined rotor and a conjugate rotor designed by variety of parameters. Such rotors can reduce noise and vibration as operation.